JP2647696B2 - Surface modification method for plastic parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for modifying the surface of a plastic component such as used in an automobile body.

(Prior Art) Conventional methods for modifying the surface of plastic parts include the following.

(A) Conventional coating method A method of applying a one-pack type paint using acrylic lacquer or chlorinated polyolefin resin or the like as a base resin or a two-pack type urethane paint using an acrylic polyol resin as a base resin on the surface of a plastic component, B) Winding vinyl chloride A method of applying an adhesive to the resin base material and pressing the vinyl chloride skin material.

(Problems to be Solved by the Invention) However, in such a conventional method for modifying the surface of a plastic part, in the coating method, a hard base resin is used, so that the coating film becomes hard and a soft feeling is obtained. Cannot be realized. Further, in the vinyl chloride winding method, there is a problem that since the bonding accuracy is required, the yield of the process is poor and the cost is increased.

(Means for Solving the Problems) As a result of various studies on the problems to be solved by the conventional display modification method for plastic parts, the present inventors have found that the elongation percentage at 20 ° C. coefficient of friction 0.5-0.8, a soft-based two-liquid type urethane paint having coating film properties of the initial elastic modulus 60~150kg / cm ^2, by coating with a thickness of 20 to 150 [mu] m, software touch the surface of the plastic part It was confirmed that a texture similar to leather was imparted, and the present invention was achieved.

The plastic parts applied to modify the surface by the method for modifying the display of plastic parts of the present invention include:
Acrylonitrile-butadiene-styrene copolymer (AB
Parts such as S) resin, polypropylene (PP) resin, plastic parts for automobiles made of PP composite and the like can be exemplified.

(Operation) Next, the operation will be described.

Here, the "texture of leather" can be expressed in three ways: (a) slipperiness → coefficient of friction (b) slimyness → initial elasticity (c) softness → elongation rate. To apply, a soft paint having a coefficient of friction of 0.5 to 0.8, an initial elastic modulus of 60 to 150 kg / cm ² , and an elongation of 60 to 180% (20 ° C.) is applied to a thickness of 20 to 150 μm.
It is effective to paint with. If the friction coefficient is smaller than 0.5, a plastic feeling is produced, and if it is larger than 0.8, a rubber-like feeling is obtained. On the other hand, when the initial elastic modulus is higher than 150 kg / cm ^{2, the} feel is hard, and when it is lower than 60 kg / cm ² , the strength of the coating film is insufficient.
If the elongation is less than 60%, the soft feeling disappears and 180%
If it is larger, a sticky feeling is generated. If the film thickness is less than 20 μm, a soft feeling cannot be obtained, and if it exceeds 150 μm, it takes a long time in spray coating and disadvantages such as sagging and tearing tend to occur, which is not preferable.

As the soft paint used in the present invention, isocyanate-cured 2 which is excellent in various properties such as adhesion and weather resistance.
A liquid polyester-based urethane coating, particularly a two-pack polyester polyol-based urethane coating is most suitable. Other paint resin systems that are rich in stretchability and elasticity of the coating film include melamine-curable polyesters and two-pack acrylic urethanes, but both have insufficient balance between flexibility and various properties. The former, in particular, requires forced drying by baking at a high temperature, and thus has a drawback that the heat resistance of the plastic material to be coated is restricted.

As the polyester polyol of the two-pack polyester urethane coating, the number average molecular weight is 1000 to 5000, and the hydroxyl value is
A type with excellent flexibility of 60 to 200 is good. That is, when the number average molecular weight is less than 1,000, the coating film tends to be brittle, and when the number average molecular weight exceeds 5,000, the solubility in a solvent is reduced, which causes a problem of spray workability (stringing, insufficient film thickness). Also, hydroxyl value 60
If it is less than 200, the toughness of the coating film is low. If it exceeds 200, the coating film is too hard to obtain a soft touch.

Hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI),
Various modified polyisocyanates such as xylylene diisocyanate (XDI) can be used, but in addition to the extensibility and elasticity of the coating, the weather resistance and adhesion required for coatings for plastic parts such as automotive plastic parts HMDI-based polyisocyanates having excellent properties such as water resistance and water resistance are suitable. The amount of the curing agent added is such that the equivalent ratio of the hydroxyl group to the isocyanate group of the polyester polyol (NCO group / OH group) is 0.
A range from 5 to 2.0 is preferred. That is, if the equivalent ratio is less than 0.5, a large amount of unreacted hydroxyl groups remains, and the curability and durability of the coating film are inferior.If the equivalent ratio exceeds 2.0, the side reaction of excess polyisocyanate causes the flexibility and adhesion of the coating film. Decrease.

(Examples) Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The following parts are based on weight.

Examples 1 to 4 According to the respective formulations of Examples 1 to 4 shown in Table 1, each of the blended compositions except the matting agent was first kneaded for 2 hours with a paint shaker (manufactured by Toyo Seiki), and then the matting agent was removed. What was added and stirred for about 10 minutes with a high-speed disper was used as a main ingredient.

To 25 parts of the obtained base material, as a curing agent, a polyisocyanate resin varnish, Polyhard R (Origin Electric Co., Ltd.)
10 parts, mixed solvent of equal amount of xylene and butyl acetate, and spray viscosity of Ford cup #
The temperature was adjusted to 20 seconds at 4 (20 ° C.) to obtain the coating compositions of Examples 1 to 4.

Next, each of the coating compositions of Examples 1 to 3 was applied to an ABS material (TRB, manufactured by Mitsubishi Rayon Co., Ltd., trade name) as a plastic material (A) in the following procedure.

First, the ABS material is wiped and degreased with isopropyl alcohol, and then each test paint composition is air-sprayed.
The composition was applied to a thickness of 60 μm, set at room temperature for 10 minutes, and then forcibly dried at 80 ° C. for 40 minutes to prepare a test piece.

The coating composition of Example 4 was applied to a PP material (K-7030R, manufactured by Chisso Corporation, trade name) as a plastic material (B) in the following procedure.

First, the PP material of the plastic material (B) was washed with 1,1,1 trichloroethane vapor for 1 minute, and then as a primer, Planet PP Primer Gray K-3 (trade name, manufactured by Origin Electric Co., Ltd., diluted thinner Planet Thinner #)
301, dilution ratio: paint / thinner = 10/4, coating viscosity 11 seconds (Ford cup # 4, 20 ° C.)]
Set at room temperature for 10 minutes. Next, the test paint was applied by air spray so as to have a film thickness of 60 μm, set at room temperature for 10 minutes, and then forcibly dried at 80 ° C. for 40 minutes to prepare a test piece.

The components shown in Table 1 are as follows.

Polyester polyol resin varnish I: number average molecular weight 350
0, 80 parts of soft polyester polyol resin with hydroxyl value of 100 and acid value of 5, toluene and methyl isobutyl ketone (MIBK)
A resin solution consisting of 20 parts by weight of a mixed solvent.

Polyester polyol resin varnish II: number average molecular weight 200
A resin solvent comprising 80 parts of a soft polyester polyol resin having a hydroxyl value of 155 and an acid value of 7, and 20 parts of a mixed solvent of equivalent amounts of xylene and methyl isobutyl ketone.

Polyester polyol resin varnish III: number average molecular weight 25
A resin solution comprising 80 parts of a soft polyester polyol resin having a hydroxyl value of 145 and an acid value of 2 and 20 parts of butyl acetate.

Titanium dioxide: CR-600 (trade name, manufactured by Ishihara Sangyo Co., Ltd.) Carbon black: MA-100 (trade name, manufactured by Mitsubishi Kasei Co., Ltd.) Additive: DC-3 (trade name, manufactured by Toray Silicone Co., Ltd.) Solvent: Equivalent mixed solvent of toluene and methyl isobutyl ketone Matting agent: Syloid 161 (Fuji Devison Chemical Co., Ltd.)
As described above, the coating film performance was evaluated for the plastic test pieces to which the coating compositions of Examples 1 to 4 were applied, and the physical properties were evaluated by the following test methods. It describes in.

In addition, the elongation and the initial elastic modulus of the coating film physical properties test was performed on a polypropylene test piece using the test paint as a coating film.
It was applied so as to have a thickness of 0 μm, and after being forcibly dried under the above conditions, a 5 mm-width knife cut was made on the coating film and then peeled off to obtain a sample. The test apparatus was a Tensilon STM type tensile tester (manufactured by Orientec Co., Ltd.) at a sample length of 6 cm, a tensile speed of 5 mm / min, and a temperature of 20 ° C. Further, the acrylic lacquer of Comparative Example 3 could not be tested because the coating film was brittle and it was difficult to prepare a sample.

The coefficient of friction was determined by KES
-With FB4 (Kato Tech Co., Ltd.), load 50g, pressure 10
g, measured under the conditions of a sample moving speed of 0.1 cm / sec. Comparative Example 1 The same procedure as in Example 1 was carried out except that the paint film thickness was changed to 15 μm.

Comparative Example 2 Planet PZ, a two-pack acrylic urethane ABS paint
Matte Gray (Origin Electric Co., Ltd., trade name) 40
To 10 parts of the mixture, 10 parts of the same curing agent as in Example 1 and a mixed solvent of an equal amount of xylene and butyl acetate were added, and the spray viscosity was adjusted to 14 seconds with a Ford cup # 4 (20 ° C.). A coating composition was obtained. Next, this coating composition was applied to the ABS material of the plastic material (A) in the same manner as in Example 1, and the coating film performance and physical properties were measured. The results are shown in Table 2.

Comparative Example 3 One-pack acrylic lacquer ABS paint, Planet AX
To a matte gray (trade name, manufactured by Origin Electric Co., Ltd.) was added a mixed solvent of an equal amount of xylene and butyl acetate, and the spray viscosity was adjusted to 12 seconds with a Ford cup # 4 (20 ° C.). A coating composition was obtained. The coating film performance and physical properties of this coating composition were measured in the same manner as in Comparative Example 2, and the results are shown in Table 2.

(Effects of the Invention) As described above, the present invention provides an elongation rate of 60 to 180% (20 ° C) and a friction coefficient of 0.5 to 0.
8. The two-component urethane paint with a coating property of 60 to 150 kg / cm ² with an initial elastic modulus of 60 to 150 kg / cm2 is applied to a film thickness of 20 to 150 μm, so that the surface of plastic parts can be made soft and leather efficiently with a soft touch. The effect of being able to be modified to have a similar texture is obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Toyama 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. Person Minoru Fujisawa 1965-1 Kume, Tokorozawa, Saitama

Claims (1)

(57) [Claims] An elongation at 20 ° C. of 60 to 180%, a friction coefficient of 0.5 to 0.8, and an initial elasticity of 60 to 150 on the surface of a plastic part.
A two-pack urethane paint with a coating film property of kg / cm ^{2 with} a film thickness of 20
A method for modifying the surface of a plastic part, characterized in that the surface of the plastic part is softened by painting with a thickness of up to 150 μm to give a texture similar to leather.